PAO is an acronym for polyalphaolefins; these oils are often referred to as synthetic hydrocarbons. The base fluids that make up a PAO compressor oil are likely the most widely used variety of synthetic oil blends. This is mainly attributed to their ability to maintain performance in spite of temperature extremes and their physical similarity to - but increased performance over - petroleum-based fluids. Synthetic PAO Compressor Oils are intended for use in types of air compressors including = centrifugal, reciprocating, and rotary screw compressors and may be especially useful in situations where mineral oil-based products are not up to the task of lubricating in severe applications.
These synthetic oils are measured in the same way as mineral-based oils when considering viscosity. ISO VG 32 oils that are also PAO-based have an average, midpoint viscosity of 32 mm2/s (or cSt).